title: Longitudinal study of dental caries prevalence and incidence in the rapakivi (high fluoride) and olivine diabase (low fluoride) areas of Laitila, Finland.
abstract: This paper is a continuation of the author's study published in 1975. The teeth of the school children included in the study were first examined in 1952, re-examined in 1972 and subsequently at 5-year intervals. Children in the village of Salo had drinking water with a high fluride content and those in the village of Suontaka drank water with a low fluoride content. In the first examination, the Salo children showed a caries prevalence, measured with the DMF inxed, ca. 67% lower than the Suontaka children. With some exceptions, such as the first molars, the absolute differences in caries prevalence between subjects from the two villages had remained practically the same throughout the years. By the 1987 examination, the difference had been reduced, measured with the DMF index, to about 23% and with the DMFS index, to about 28%. In the last 5 years (1982-87), the DMFS index of the Suontaka pupils increased by 2.5 and that of the Salo pupils by 4.1. In the preceding two 5-year periods the increment in each group was ca. 7.0%.
authors.forename: A
authors.initials: A
authors.lastname: Pärkö
mesh_terms: D000328:Adult; D004245:DMF Index; D003731:Dental Caries / Q000453:epidemiology*; D005260:Female; D005387:Finland; D005459:Fluorides / Q000032:analysis*; D005843:Geography; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D014881:Water Supply / Q000032:analysis*
chemical_list: D005459:Fluorides